Welcome to Photo.net: A Community of Photographers

Home > Equipment > UV filters

Filters - UV or not UV?

by Bob Atkins; revised April 2007

[See also Philip Greenspun's article on filters]

UV filters are supposed to block UV light. So, for the newcomers to photography let's first look at what UV light is and why you would want to block it.

The "traditional" visible spectrum runs from red to violet. Red light has the longest wavelength and violet the shortest. Light which has a longer wavelength than red is called infrared, and light which has a shorter wavelength than violet is called ultra violet or UV. The wavelength of light is measure in units of nanometers (abbreviated as nm), and 1nm is a billionth of a meter (that's a US billion or 1000 million, not a UK billion which is a million million!). Light shorter in wavelength than about 400nm is called ultra violet, light longer in wavelength than 700nm is called infrared.

So now we know what UV light is, why would be want to block it? Well the answer lies in the way that color film works. There are basically three color sensitive layers, one sensitive to red light, one to green light and one to blue light. The blue layer not only responds to blue light, but also to UV light, so if there is a lot of UV around the blue sensitive layer gets extra exposure and the final image takes on a blue color. Since film isn't normally sensitive to infrared, you don't need an infrared blocking filter. Interestingly though, digital sensors are infrared sensitive and most digital cameras have an infrared blocking filter built in.

Now there isn't usually a huge amount of UV around at sea level. There is some (that's what gives you a suntan or a sunburn) but most of it is scattered by the atmosphere. However as you gain altitude, for example by going up a mountain, the amount of UV increases. Under these conditions a UV filter can prevent a blue cast in photographs.

Since UV filters look clear and neutral to the naked eye, some people also use them as a protective filter which they leave on their lens at all times. Some people think this is a good idea, other question the wisdom placing a $20 filter in front of a $1000 lens and potentially affecting image quality. Both schools of thought have some valid points. It's your choice.

So if you buy a UV filter, you'd expect it to block UV right? Well, sometimes you'd be wrong as the results of this test show. I've looked at the range between 350nm and 400nm for UV blocking since the glass used in almost all lenses will itself block any light with a wavelength shorter than 350nm, so you don't need help from a filter there.
 

The Tests

The filters were measured using a calibrated UV/visible spectrophotometer which I had access to at the time of the tests.

The plot below shows the transmission characteristics of a number of "UV filters". There are 3 "generic" type filters, a Millennium (marked "made in Japan"), a second Millennium (this one marked "made in China") and a Promaster, plus 3 "name brand" filters, a Tiffen UV protector, A Hoya UV filter and a B+W UV filter. As you can see from the plot, the 3 "generics" along with the Tiffen UV protector really did not cut any appreciable UV down to 350nm. The Hoya and B+W filters showed definite UV absorption, the Hoya being more effective at UV blocking.

Looking more closely at the plots for the four filters which did not show much UV absorption you can see that they are all quite similar. In fact the Millennium UV (Japan) and Promaster UV filters appear to be identical. They may well have been made by the same factory and branded with two different names. The Tiffen looks close enough that it too might even come from the same factory, or at least use the same type of glass.

In addition to the UV filters I also looked at a three filters often used in place of a UV filter (i.e. filters which some photographers keep on the lens at all times as protection). These are the Hoya 81B, the Tiffen 812 and the B+W KR1.5. All three are warming filters in that they shift the color balance towards the red (warm) end of the tonal range. I also included a Hoya circular polarizer, just because I had one around. 

As you can see all three of the warming filters were effective UV absorbers, as well as slight absorbers in the blue and green regions of the spectrum (which is what makes them warming filters). The polarizer absorbed slightly more in the UV than the visible, though I wouldn't call it an effective UV absorber.

Perhaps a more informative way of plotting the data is as a bar graph comparing transmission in the visible range (400nm to 650nm) to transmission in the UV range (350nm-400nm). This is shown below. Added to the group is data for a Tiffen Haze-1 filter, which you can see is VERY effective at blocking UV and a Hoya 1B, a slight warming filter. The four filters on the left clearly don't really absorb UV any more than they absorb visible light. They may be fine as lens protectors but don't make good UV blockers.

Another interesting way to look at UV blocking is to calculate the effective number of stops that the filter attenuates for the wavelengths between 350nm and 400nm compared to transmission in the visible. The data are plotted below on that basis. For example the Tiffen Haze-1 filter looks like a 5 stop filter to UV wavelengths in that range, while the low cost generics and the Tiffen UV protector show less than 0.1 stop attenuation of UV. 

This last plot makes the order of UV absorbing effectiveness quite clear

  • The Tiffen Haze-1 is best. It's a neutral filter so color balance is unaffected.
  • Next is the Tiffen 812. Good UV blocking if you also want a warming filter
  • The Hoya 81B is very similar to the Tiffen 812. 
  • The Hoya UV filter comes next, neutral, but with 2 stops of UV blocking.
  • The B+W KR1.5 gives about 1.5 stops of UV blocking with slight warming.
  • The Tiffen polarizer gives less than a stop of UV blocking, but that's not why you use a polarizer!
  • The B+W and Hoya 1B aren't very good UV blockers. The 1B is slightly warming
  • The three "generics" and the Tiffen UV protector are pretty useless for blocking UV, though they may make fine, neutral, lens protectors.

My Pick

What I actually use when I need a UV filter or a protective filter is a Tiffen 812. Usually, for the type of work I do, a warmer image isn't a problem, indeed it's often desirable. I also like to minimize the number of filters I carry so my 812 serves three functions. It blocks UV, it protects the lens and it's a warming filter. Some people use an 81B for this, but I slightly prefer the color shift of the 812. Not everyone wants a warming filter, so the clear winner for a neutral filter that really bocks UV is the Tiffen Haze-1, though the Hoya UV should also be pretty effective.
 

More

© Copyright 2003-2007 Robert M. Atkins.

Readers' Comments


Add a comment



Luis Bascones , October 16, 2003; 11:32 A.M.

Personally, the only graph I really find useful is the first one - the frequency response graph. I find the other ones a little too simplistic, probably because they bundle all wavelengths into two bands, hence loosing information that I find important. This probably comes from my EE background and remembering some of the details about filter design - there is No such thing as a perfect filter. Also, I would have loved seeing the freq response curves for the Tiffen haze filter to confirm your recommendation.

As far as the filters that have freq response profiles in there, it would seem to me that it’s almost a toss when choosing between the B+W UV and the Hoya UV. The tiffen lets in some UV, but it allows all desired blues to come in. The Hoya does a better job at cutting of the UV, but then again also kills some desired blues, effectively warming the image just a tiny bit. Of course, this may be a desirable effect so it probably still is a better option.

Anyway, thanks for another great and insightful article.

LuisB

Olivier GALLEN , October 16, 2003; 02:25 P.M.

Thank you Bob for this very informative article. Maybe some additionnal info: I checked the spectral sensitivity curve for my usual film, and found that the blue layer is not so sensitive below 400nm. So, before choosing a UV filter, you may want to check how your own favorite film does react to UV, in order to get an idea of the whole thing. I also thought that most modern Multi-Coated lenses had good UV filtering in it, so this could also affect your choice. Olivier

Hemendra Chonkar , October 16, 2003; 02:42 P.M.

Hi,

Thanks Bob, for an informative article.

Since this discussion is with reference to the Blue layer in film I was wondering whether it applies to the imaging sensors in DSLRs as well.

Put in another way, does UV light affect the imaging sensor of the DSLR enough to cause color shifting ? I have noticed a blue cast on some my images on my 10D and maybe the reason is that I did not have a UV filter on.

The attached image is stitched panorama where all the individual images seem to have the blue cast.

Regards, Hemen

Image Attachment: PhotoNet_Aruna-Parth-Neptun.jpg

Yaron Kidron , October 16, 2003; 02:49 P.M.

Great document, uncle Bob! Would it is sensible to assume that there is a difference in UV absorbance between film and digital?

John Ampe , October 16, 2003; 07:03 P.M.

Outstanding article!! But after reading it, I find myself no closer to answering the simple question that I'm sure all of us have: should I use a UV filter, and if so, when? Thanks to this article, we know that some filters do actually remove some UV. But does this make a visible difference in any real-world situation? Can anyone post examples, with and without a UV filter, where there is a perceptable difference? If such examples exist, can anyone categorize the situations where a UV filter will make a visible difference? And of course, how do various films differ in sensitivity?

Mark Bouquet , October 16, 2003; 08:59 P.M.

An article like this should be published in one of the major photography magazines, but probably won't be because it makes clear the fact that many of the filters being sold are really pretty useless. It won't be published because those publications serve their advertisers, and not their readers. (JMHO)

I think this article is a bit dated already. I say this because filter technology is making technological leaps forward in recent years, and the most recent designs are not taken into account here. A case in point is the relatively new "Pro 1 UV" filters introduced by Hoya. The transmission curve for this filter in their most recent catalog shows an almost ideal steep straight falloff in transmission to zero at 400nm. (The published graph for their standard UV filters is essentially identical to the one published in this article.) There's also a Pro 1 "Skylight" filter offered by Hoya, though they don't give a transmission curve for it in their catalog. Admittedly, these new filters are expensive, about $45.00 in the 49mm size that I use (B&H), compared with about $10.00 for a Tiffen Haze-1, but they have the advantage of being made from dyed optical glass with state of the art multicoatings, compared with Tiffen's laminated construction and no anti-reflection coatings. If the intention is to eliminate UV while not changing the color balance of the visible light, and to retain the highest possible optical characteristics, these state of the art designs render most of the other filters mentioned in this article obsolete.

Still, I don't want to dismiss the value of Bob's effort here. This is the clearest presentation of the issues regarding management of UV that I've seen. Now we can better understand this factor in our photography, and we're able to make informed decisions about how to deal with it. Thanks Bob!

Assad Khan , October 16, 2003; 09:46 P.M.

A very good read for a newbie photographer like myself. I have been asking the questions that this article answers ever since I started this hobby. The Tiffen Haze-1 filter seems to be the best, but it also is very expensive ($146 at B&H) for a person like me, I think I will stick with Hoya ($20-$50).

-Assad EDITED: Sorry, I was mistaken, the Tiffen Haze-1 filter costs about $13. *Phew*, thats a relief.

Luigi Moccia , October 17, 2003; 09:30 A.M.

Thanks for the accurate test, but still it leave me some doubts. As also Olivier Gallen pointed out, how about the UV blocking of the lens itself? Are regular lens already effective in cutting the UV portion of the spectrum or not? I would be curious about a test of the system lens+filter respect to the lens alone.

Jesper de Jong , October 18, 2003; 02:42 P.M.

Interesting article, but I'm missing one thing: Are digital sensors sensitive to UV light, just like film? Is there a difference between different kinds of sensors (CCD, CMOS, etc.)?

Douglas Herr , October 18, 2003; 04:03 P.M.

Luigi makes a good point - what about the UV-blocking properties of lenses? Some manufacturers claim to have UV-blocking cements and coatings.

Bob Atkins , October 19, 2003; 12:23 P.M.

If you read the article carefully you'll see...

...I've looked at the range between 350nm and 400nm for UV blocking since the glass used in almost all lenses will itself block any light with a wavelength shorter than 350nm, so you don't need help from a filter there...

Yes, lenses do block short wavelength UV, but do not normally block much light between 350nm and 400nm - and that's exactly where UV blocking filters do their work (or don't, as the case may be!).

The question of whether you need UV blocking filters with digital cameras is a good one, but there's probably no general answer. Certainly CCDs and CMOS sensors, which both use silicon photodetectors, are intrinsically UV sensitive. Whether any manufacturers us a UV blocking filter I don't know. Most (all?) use IR blocking filters. I suspect they don't use particularly strong UV cut filters since most of the time they aren't needed.

Whether UV filters are needed at all is another good question. Probably most of the time the answer is no. Maybe high on a mountain where UV is stronger than at sea level they are useful if you are shooting slide film. My guess is that if you're shooting print film or digital, any blue cast caused by UV can be removed by small correction in printing filtration or by color balancing digital files.

On the other hand, if you're one of those people who really want a lens "protector", you migh as well get one that also blocks UV, since blocking UV does no harm and may do some good under some circumstances.

Conrad Smith , October 19, 2003; 04:00 P.M.

It would be useful to find similar information about different brands of 81B-, 81C- and 81E-type warming filters, particularly for those who live or photograph at high altitides where the blue cast in chromes is substantial.

Fabian Gonzales , October 19, 2003; 10:41 P.M.

Bob - as usual, a very well written and informative article. Thank you.

I first learned how essential UV filters are when trekking in the Himalayas. Especially when photographing in the shadows, my images clearly took on a blue tinge. At altitude, a good UV filter is essential. Also, one thing that is easy to forget is that polarizer filters do not filter UV very well. And since most people unscrew their UV filters before attaching the Polarizer, I recommend one of the new Pola + UV filters, especially if you are photographing in the mountains.

Bob Atkins , October 20, 2003; 11:36 P.M.

Shadows going blue isn't always a sign of excessive UV. Shadows are normally illuminated only by the blue sky - which is of course blue - and so shadow regions tend to be blue. Often you may be better off with a warming filter like an 812, which will block some UV as well as warming the shadows. Of course it also warms the sunlight regions.

Excessive UV usually shows up as an overall blue cast in both sunlight and shadow regions - or so I'm lead to believe. I've not personally been high enough in the mountains to notice the effect very much.

Michael Clark , October 23, 2003; 05:39 P.M.

In reference to whether UV affects digital cameras' sensors or not, I've read that UV contributes to the purple fringing we see on high-contrast photos. I have a G3 and 812 filter. Perhaps some experiments are in order. :)

Bryce JFG , October 24, 2003; 01:51 A.M.

Odd that no one has hinted at what I understand a UV/Haze filter to be good for: filtering haze. My understanding is that atmospheric haze effects can show up in a photograph that weren't obvious in the original scene, due to UV light scattering from atmospheric haze. Since the film can respond to wavelengths invisible to the eye, we see it in the picture as haze that we didn't see when we took the picture.

Am I remembering this correctly?

Richard Stum / Kinesis , October 24, 2003; 06:30 P.M.

Agreed Bryce. As mentioned above, color variations (blue cast from no or a lousy UV filter) can be adjusted in digital post production. Haze, on the other hand, is more difficult, if not impossible to remove. I would like to see some "real world" before and after samples, esp. using the Tiffen UV Haze-1 or the Hoya equal. I have noticed a big increase in haze in landscape photos with the Canon D60 compared to using film (despite the use of L-series lenses).

J. Harrington USA (Massachusetts) , October 26, 2003; 01:22 A.M.

Maybe you have explained why these high altitude images are so blue.

Emil Solomon , October 29, 2003; 12:01 P.M.

Would you please refer to using Sky Light filter insted of UV.

Eli

Stephen W. , November 05, 2003; 05:15 P.M.

Bob,

Thanks for the effort. I'm a gear head (engineer), so I liked the inclusion of the charts.

I don't generally use protective filters, but have them for hazardous duty places: Mountain with blowing snow; the beach; and volcanos (Pacaya in Guatemala for example). I moved on to using caps because 1. I've never scratched a filter, so the likelyhood of scratching the lens is small, and 2. I've seen a filter break and scratch a lens.

Steve

Nick Kiest , November 28, 2003; 04:23 A.M.

As for digital, my understanding is that it barely (note I did *not* say not) UV reactive, but radically IR reactive. Thus, all Digital cameras have very strong IR filters built-in. They are so sensitive that Kodak has made several IR version of its DCS series (quite rare, but we have two versions in our studio), where Kodak just removed the IR filter, and the IR signal overwhelms the standard light signal. Digital IR photography is quite impressive. Silicon is inherently IR sensitive (CMOS & CCD), and Silver is UV biased (and not IR sensitive).

Nick Kiest

Wojciech Pomianowski , December 13, 2003; 09:22 A.M.

High altitude is major reason for high UV radiation, but not necessarily for blue casts (I mean real overall cast and not apparent shadow blue). I have done quite a lot of photos at appx. 3000-4500 m. with no UV filter and without blue casts. Short distance photos are far less affected than panoramic ones (In deep moutain fog, I have even "succeeded" to have yellow-brownish cast). All this leads me to the conclusion that UV bluecasts occur only when altitude is combined with specific vapour conditions: the presence of condensed water droplets but not blocking fog. To put it simply: UV radiation has to scatter on something. What really counts is the volume of air between your camera and your subject.

I have recently learned how important is the second condition. I took the most UV-affected photos ever while crossing Cook Straight, New Zealand. Contributing factors were: water haze and salt scattered in the air, but definitely no altitude because it was 0 m.

Huey Stevens , December 15, 2003; 11:50 A.M.

Firstly I would like to say that I have always enjoyed the technical articles here, and appreciate that this is a resource for other photog's to draw upon.

Like the earlier EE that posted a reply, I too would like to see a spectral attenuation graph of the Tiffen HAZE-1 filter.

My choice is B+W as my UV filter for my expensive NIKON glass. This was a recommendation of the Photo sales guy who stated simply that the B+W glass was about the only filter glass that matched the quality of the NIKON glass, meaning overall sharper photo's.

The article addresses very well the UV attenuation, but gives no consideration for the sharpness of the filter. For those that follow lens sharpness tests, I am concerned about how the filter not only affects the light spectrum that is permitted to pass through the glass, but also how the filter affects the overall Modulation Transfer Function (MTF) of the lens.

For instance, I could rub vasiline on a piece of glass and then like Bob measure the decrease, if any, in the amount of UV spectrum through that filter. It would be a soft filter for sure and for example purposes it is somewhat ridiculous, but nevertheless brings up an important point. I would like to see UV attenuation vs. sharpness. I think in this category the B+W and more expensive filters will show themselves to be a better choice IF that is something that is important to you as a photographer.

Arun Dangwal , December 28, 2003; 12:55 A.M.

Thanks for all the information provided.. but it would be better if someone could provide the information like at what number of mm on lense would require what kind of UV filter.. eg. if i have Nikon 28-105mm lense then what filter should be best.. and if i have telephotic lense like Sigma 70-300mm.. than what would be the best.. because what happens is as we increase the mm on lense i have found the haze also starts increasing... i mean the picture comes out white in shade...i use +ve rolls... thanks!!! rest the information is really viatal for all..!!!

Adrian MacGregor , January 22, 2004; 09:45 P.M.

As a note to Wojciech, the reason you may have noted the effect of UV more during your trips to NZ may have something to do with the nearby hole in the ozone layer over Antarctica. Its just an assumption, but the increased UV levels that we're warned about (skin cancer, etc), may also be more obvious on film.

Guess I'll be keeping that UV filter on my lenses then!

Adrian

David H. Hartman , January 25, 2004; 02:17 A.M.

I would love to have seen Nikon L37c and L39 filters and Canon and Pentax equivalents. Not that I would like a Nikon v. Canon v. Pentax war but that I would consider buy filters from any of these companies if they performed in a way that I wish. The Nikon L39 filter is a non-multi-coated filter with greater UV filtering properties than the L37c. I greatly prefer multi-coated filters. I currently use Nikon L37c filters on most all of my lenses.

I live in a semi-arid region and consider going without a filter for protection foolishness as dust is a constant problem. I do not like to clean a lens frequently but a filter is more expendable. I surmise that those who do not use a filters for protection must live in regions with higher humidity and that that humidity helps control dust.

Dust on the front element or filter can add considerably to flare and ghost. Removing a filter in extreme conditions should reveal a spotless front element.

I also find that shading a lens when possible with a hand, hat or black card has far more effect in reducing flare and ghost than removing a filter. For longer focal length lenses a bellows type or compendium lens shade is the silver bullet to slay flare and ghost.

Nico Kamm , March 02, 2004; 05:28 P.M.

Hey folks, interesting to know but there is still the matter of the quality of the glass - the coating. Anyone knows the quality of the tiffen haze-1 or the hoya - i know the hoya g-series is coated only on one site - this is suffiecient quality - i don't know if you really nedd hmc?

Chris Wetherill , March 03, 2004; 08:29 P.M.

A simple way to test whether a "UV" filter is doing something or not in the part of the near UV which most concerns most photographers is to put it between a blacklight and something fluorescent under same. A blacklight puts out most of its UV energy at around 365nm, so if the filter doesn't have much absorption until down around 350nm then one won't see much change when the filter is between the blacklight and the fluorescent "sensor". If the filter kicks in at 370nm or above, the material will appear much darkened - even almost black if the filter is close to the material.

At sea level the difference between different filters may not be significant, but for those of us at altitude (up to 14,000+ ft here in Colorado) it makes a big difference with all B&W films and many color films.

BTW - early in 2004 B+W was coming out with a new strong UV filter designated 415, which may appear to the eye as a faint yellow filter (like a Wrattern #2B) since it absorbs below 415nm; the standard B+W 010 UV filter fails the blacklight test and thus doesn't have much absorption until down below 360 nm. I've corresponded with the tech people at B+W on this matter and can forward on the curves and such data they sent me for anyone really interested.

Clayten Hamacher , June 04, 2004; 01:58 A.M.

I think the important issue is UV attenuation. An expensive, optically neutral, high-quality, B+W UV filter is a pretty lousy UV filter if it doesn't filter UV. If you need a UV filter you *can't* buy the B+W because it *doesn't work!*

Strong language sure, but everything else is irrelevant if it doesn't work.

On the subject of filters, have you (anyone who questions the quality degredation of using filters) actually put your camera on a tripod in perfect conditions and taken one picture with a filter and another without? I've can't, nor have many others, even when shooting with pro-quality lenses. Of course a salesman will sell you the most expensive filter, especially if you proved you've got the money to buy an expensive lens, if he thinks he can. Sales people aren't the most impartial source of information on high-margin products they carry.

Dmitry Kuznetsov , June 13, 2004; 03:08 P.M.

Thanks for the interesting paper to read!

I would very much like to see here any objective data on how non-coated (UV) filters may worsen image quality (e.g. make it quasi-blurred) because of multiple reflections between the two filter surfaces (more on this one could find at http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/filter/filter-coated.html).

Personally, I can readily observe such image softening, simply looking through viewfinder of my Pentax 67II camera / Pentax M*300ED lens, with and without a Rodenstock UV/IR filter (which supposed to be the top quality filter).

Gary Morris , June 22, 2004; 04:46 P.M.

A few years ago I went up to a mountaintop to take photos of the Hale-Bopp comet and was disappointed to find that none of my shots showed both comet tails, the bluish tail was missing in every shot. Other photos I've seen of the comet usually had the faint blue tail. Afterwards I realized I had left the UV filter on the lens and suspect that's why I didn't see the bluish tail. This might be one case where you should remove the UV filter in order to capture the UV part of the scene!

Kryn Sporry , August 15, 2005; 03:37 P.M.

Ok, maybe a bit late response, but lets dig out this discussion again. So the Tiffen Haze-1 is supposed to be pretty darn good. I noticed that they have a Haze-2A as well. Does this one really work that much better? Anyway, I checked on the B&H website (I have to buy this stuff in the states as pathetic england still lives in teh dark ages. They even still use tam-tams here!!!) and for sure they have the Tiffen filters, but the example image they show with both the Haze-1 and Haze-2A is appauling! Not only did they use the same image for both filters (thereby making their findings highly dubious), but also the filtered image is way worse in detail than the unfiltered image! Can someone tell me if the Tiffen filters affect the detail/resolution of the image?

Sue BLOCK , February 08, 2007; 12:45 A.M.

UV filter is important to protect the lens. A Polariser filter guards against reflections from glass etc.

I was wandering whether anybody could assist me

I am new to the forum and

I am wishing to purchase a circular Singh-Ray plain glass polariser filter. I hear it is an excellent filter. I am wishing to use a cokin P holder as I not wanting to buy two polariser filters one for my Nikon 70-300 and one for my Tokina 12-24mm lens.

Here is the thing. So far I have been unable to access the filter in Australia. So if there are any Australians out there who can assist on information.

From the Singh-Ray website there only seems to be a warming polarising filter which I do not want. As the plain glass (resin) would be better.

The cost is pretty steep for a filter and I am prepared to consider an equally good polariser filter. My constaint is that the filter needs to be able to fit into the Cokin P holder.

Expert advise would be appreciated.

Sue

Kamran M , March 28, 2007; 08:52 P.M.

I found this link and I think some of explanations about haze and UV filters might help to shed some light on this discussion: http://dpfwiw.com/filters.htm#uv

Albert Urso , April 20, 2007; 01:30 A.M.

My experience with the Hoya Super UV(0) is that there is a 100-200 degree difference in temp. on the warmer side. My question is does that shift some colors when I compensate with white balance? This was a big suprise to me because I thought Nikon ran a little blue but obviously not enough to make that neutral.

peter hildebrandt , July 13, 2007; 02:36 P.M.

Hi to all!! I am looking to set up equipment to photograph specimens while exposed to UV light at 185nm, 254nm and 360nm in a dark chamber.

I'll be looking for flourescence and absorption in the samples but I wonder how many UV filters I'll need on the 35mm camera to cut UV from a 4 watt lamp at 2 feet at the wavelengths above while using 400 speed color film. Thanks!!

Landrum Kelly , August 26, 2007; 10:52 P.M.

Since this thread has gone on for some years, I was wondering if anyone has any new info regarding the effect of UV light on CMOS and CCD sensors. I presume that it is still the case that digital sensors are more sensitive to IR than to UV radiation, but I am wondering if anybody has any quantified results to share--and whether the numbers have changed as digital sensors (and related technology) have evolved.

--Lannie

Klaus Shuler , April 07, 2008; 12:13 P.M.

Just thought you migth like to see this web page about filters. If you are using a filter mostly for protection, then it seems to me the thing you want is the most transmission of light. Decreased transmission is due to reflection, and this contributes to flare. IF you have a nice multicoated lens, why stick a piece of cheap flare prone glass to the front? YOu can see the polish website here for examples of what I mean.

http://www.optyczne.pl/5.1-Inne_testy-Test_filtr�w_UV.html

THe site is in polish but thepictures anid graphs speak for themselves, and you can really see the effect of lack of multicoating on the amount of flare in an image. THe tiffen filter came out TERRIBLY in these tests.

Klaus -- http://bokehtests.com/Site/About_Bokeh.html

Mike Anderson , June 02, 2008; 06:41 P.M.

Helpful article, I think this should help newbies gain a greater understand of UV light.

Paul Verizz , July 23, 2008; 01:43 P.M.

A great job here! And obviously the thread is now running into its fifth year, so it must be helpful.

My only thought is that taking shots on the mountain in Colorado always showed a lot of haze. That's mostly with digital but also color film. I bought a 49mm Tiffen Haze 2 from B&H for $25. I can't say that I did A-B comparisons, but I know that there is nothing better and I might as well use it. Sadly, lost the first filter, had to buy another. Why couldn't it have been a generic skylight??


Add a comment